Advanced C: recursion and files

Two lessons: the function that calls itself and the call stack, then reading and writing files directly through the operating system.

OverviewA continuously-growing reference covering this section's advanced projects: from recursion and the call stack, to working directly with files through system calls, entirely independent of the actual tasks you need to sol
RecursionA way of solving different from loops: a function that calls itself on a smaller copy of the same problem until it reaches a case simple enough to solve directly.
Working with FilesFrom working only in memory to dealing directly with the operating system to read and write files, with low-level system calls instead of library functions like fopen.
Wrap-up and resourcesThe best outside resources for these lessons, classified by kind and level. All are open to everyone and need no account on any platform. Use the filters to narrow the list.